Field of Invention
The present invention relates generally to the problems associated with waste in animal confinements, and more specifically, to separation methods and systems for converting high concentrations of animal wastes into nutrients and other useful products.
Related Art in Technical Field
The cleanup and handling of cattle, swine and poultry manure has become a critical issue in the management and disposal of animal waste. Animals have been raised for centuries for food and previously such animals grazed in fields or pens. Current methods of raising livestock include housing in high concentration within a confined space. Numerous drawbacks of such confinement include high concentrations of waste that must be removed from the confined space.
The manure produced must be removed regularly to ensure adequate sanitation and to prevent disease. One manure removal method is to flood the housing area with water in order to wash away the manure. The resulting effluent, that being a liquid/solid manure slurry, is typically directed through pipes or channels to a manmade slurry pond or lagoon, where the solids and particulates settle to the bottom and the animal waste decomposes. After some decomposing, the waste can be applied as a fertilizer. Additionally the liquid/solid manure can be directed to a biodigester to capture some of the gaseous components of the manure and use the gases for energy, thereby reducing air quality issues of manure accumulation and storage. However, the remaining liquids and solid from biodigestor processing must still be addressed to minimize loss of nutrient or contamination of lagoons, fields, drinking water, wells, or fresh water streams or lakes.
Notably, prolonged mixing of solid and liquid wastes in a waste manure lagoon can result in the transfer of a significant amount of nutrients from the solid material to the surrounding liquid, so that the solids become depleted of nutrients that may be desirable in a manure fertilizer. However, the liquids become loaded with nitrogen, phosphorus and salts to such an extent that they must be either limited in their irrigation use, or mixed with fresh water to lower the proportion of these substances. In other words, the useful qualities of both the solid and liquid portions of the slurry mixture are degraded over time in a slurry pond or lagoon.
Further, the environmental impact can be substantial when applying the waste to fields. Such environmental issues may include groundwater leaching from the lagoon causing contamination of groundwater and/or streams and sand soil contamination. Additionally, the high volume of solid waste manure, coupled with its use as fertilizer in local fields, results in increased levels of phosphorus, nitrogen, and potassium in the soils. This may allow such chemicals to also leach into drainage waters and run-off streams. The high volume of liquid waste manure, coupled with its use as fertilizer in local fields, results in increased levels of nitrogen rich ammonium and ammonia in the soils. This may allow such chemicals to also leach into drainage waters and run-off streams.
There has been increasing publicity and stricter environment requirements and enforcement because of the continuing concern over maintaining water quality in watershed areas due to the release of manure as normal operational discharges from dairy cattle, beef cattle, swine, poultry and other concentrated animal feeding operations. Current technologies for separating solids and nutrient components of such animal waste have limitations, are costly to operate, and result in the use of large quantities of fuel and labor in order to provide solid and water-based effluents that can either be recycled or are environmentally acceptable to spread on farmlands.
Thus, what is needed is an improved process and separation system for treating animal waste that is low in capital equipment cost, low in waste transportation cost, prevents pollution of water resources, simple to operate, and that provides solid and liquid effluents containing beneficial and useful products to generate a sustainable supply of nutrients critical for food production.